Apparatus for sharpening drills by means of a grinding wheel



0. AMIET Nov. 10, 1959 APPARATUS FOR SHARPENING DRILLS BY MEANS OF AGRINDING WHEEL Filed Aug. 28, 1957 2 Sheets-Sheet 1 0. AMIET Nov. 10,1959 APPARATUS FOR SHARPENING DRILLS BY MEANS OF A GRINDING WHEEL FiledAug. 28, 1957 2 Sheets-Sheet 2 MEEEE A M FIG 3 United States PatentAPPARATUS FOR SHARPENING DRILLS BY MEANS OF A GRINDING WHEEL OscarAmiet, Geneva, Switzerland, assignor to Christen & Co. A.G., Bern,Switzerland, a Swiss firm Application August 28, 1957, Serial No.680,728

Claims priority, application Switzerland September 28, 1956 3 Claims.(Cl. 51-219) My invention has for its object an instrument forsharpening drills by means of a grinding wheel. Said apparatus ischaracterized by a carrier for the front end of the drill, said supportbeing fitted revolu-bly over a pivot parallel with the axis of thegrinding wheel and located in the immediate proximity of the latterwhile a carrier for the rear end of-the drill is also carried revolublyon said pivot through the agency of an arcuate slider adapted to movewith a view to adjusting the cutting angle over a drum, mountedrevolubly around a rod extending radially of the pivot, to provideadjustment of the angular setting of the drill.

I have illustrated by way of example a preferred embodiment of myinvention together with a detail modification in the accompanyingdrawing, wherein:

Fig. l is a perspective view of the apparatus;

. Fig. 2 is a sectional view thereof through the axis of the grindingwheel;

Fig. 3 is an elevational view of a detail on an enlarged scale;

Fig. 4 is a view of a modification of said detail shown in Fig. 3.

The apparatus illustrated is particularly suitable for the sharpening ofdrills the diameter of which ranges between 0.1 and 2 mm. It includes asupport 1 fitted on an upright 2. A shaft 3 carrying at one end abellshaped grinding wheel 4 is revolubly carried inside a socket 5rigidly secured inside the support or head-stock 1.-' The position ofsaid socket is longitudinally adjustable and it is secured in positionby a screw 6 threadedly engaging the support and the end of which bearsagainst the bottom of the longitudinal groove 7 formed in the socket.The shaft 3 is fitted inside the socket 5 with some axial clearance andits rear end engages a stop which is adjustable in an axial direction,said stop being constituted by a screw 8 engaging said rear end andscrewed inside a stationary support 9, said screw being locked in itsturn by a further screw 10 (Fig. 1). The axial location of the grindingWheel may thus be adjusted in a manner such as will compensate for itswear. The shaft 3 carries furthermore a grooved pulley 11 driven by amotor which is not illustrated.

The drill is fitted on the apparatus through the followingmeans: a lug1a of the head-stock 1 is provided with a pivot 12, the axis of which isparallel with that of the grinding wheel. A sleeve 13 is revolublymounted on said pivot with the interposition of a ball bearing 14. Saidsleeve carries radially on the one hand a carrier 15 for the front endof the drill and on the other hand a rod 16. The carrier 15 is providedwith two orthogonal bearing surfaces 15a and 15b (Fig. 3), the axis ofthe rod 16 lying in the plane of the surface 15b perpendicularly to theaxis of the pivot 12.

A drum 17 is revolubly carried by the rod 16. The outer surface of saiddrum forms a part cylindrical slideway the axis of which extendsradially of the rod 16 and over which may rock the arcuate slider 18provided with a slot 19 through which the rod 16 extends.

Said rod the outer end 16a of which is threaded carries a nut 20 whichserves for locking in position the drum 17 and the slider 18 afteradjustment. Said nut 20 which is longitudinally elongated is outwardlyknurled so as to form also a handle controlling the movements of thedrill with reference to the grinding wheel. The arcuate slider 18carries at one end a bracket 21 (Fig. 1) on which is fitted a stud 22engaging the axial bore inside a chuck 23 carrying the drill'24. Saidstud forms the end of a screw 22a provided with a knurled control shank22b and a scale-carrying drum 22c moving past a stationary mark 25. Theaxial position of the stud 22 and consequently that of the chuck maythus be adjusted in a highly accurate manner. The chuck includes twosections 2311 and 23b which are telescopically assembled and are lockedaxially with reference to each other by means of a screw 26. The chuckis removably fitted on the apparatus and it is held in position on theone hand by the drill resting through its front end in the carrier 15and on the other hand by the stud 22 engaging its rear axial recesswhich is not illustrated. The rear section 2312 of the chuck is providedwith an enlarged part 230 forming a divider. To this end, twodiametrically opposed notches. 27 are formed in said extension forengagement by the end of a catch 28 sub jected to the action of a returnspring carried by the bracket 21. Said catch defines thus two stableangular positions for the chuck 23, said positions lying at from eachother and corresponding to the two operative cutting surfaces of thedrill. It is also possible to provide a larger number of notches 27 whensharpening drills having more than two cutting surfaces.

The apparatus operates as follows: the drill is introducedinto the chuckand locked therein and the chuck is then set in position in theapparatus. The length of the chuck is adjusted through a sliding of itssection 23a with reference to its section 2312 after which the screw 26is screwed in when the drill rests near its front end over the carrier15. The adjustment of the axial position of the drill may be perfectedthrough the agency of the screw 22a. Before the screw 26 is actuallytightened, the section 23a of the chuck is caused to rock around thesection 23b which is held against rotation by the catch 28, the outerend 28a of which may be shifted by operators finger, until one of thecutting ridges of the drill is brought into a radial plane of thegrinding wheel as illustrated in Fig. 3. A magnifying glass the positionof which is adjustable makes this operation easier. The control handle20' is then released so as to allow the drum 17 to rotate round the rod16 and to adjust thus the angular setting of the drill. 17 carries amark 30 cooperating with a scale 31 provided on the sleeve 13. Theslider 18 is then shifted with reference to the drum 17 forming itsslideway so as to define the cutting angle of the drill. Said angle maybe checked through the mark 32 on the drum 17 cooperating with a scale33 on the slider. The nut-shaped handle 20 is then tightened so as tolock both the drum 17 and the slider 18 in their adjusted positions. Thesystem carrying the drill is then caused through a shifting of saidhandle 20 to rock bodily round the axis of the :pivot 12 so as to makethe tip of the drill register with the edge of the grinding wheel 4. Thechuck 23 is finally shifted angularly by 180 and a further operation ofthe handle 20 leads a second time the drill into registry with thegrinding wheel for the sharpening of the second cutting surface of thedrill.

It should be noticed that the different rocking movements of thedrill-carrying system round the axis of the pivot 12 are limited by apin 34 carried by the sleeve 13 (Fig. 2) and moving inside a notch 35formed inside an arcuate grooved sector 36 forming thus a double To thisend, the drum 3 abutment. Said sector is frictionally fitted over aconical terminal bearing surface 12a of the pivot 12, the amount offriction being adjusted by a nut 37. It is thus possible by urgingslightly-the'handle 20 beyond its normal path to'shift the doubleabutment 36 and to modify thereby the range within which thedrill-carrying system rocks freely.

In the modification illustrated in Fig. 4, the member 38 forming thecarrier for the front end of the'drill is provided with a bearingsurface 38a corresponding to the bearing surface 15a in the firstembodiment illustrated in Fig. 3, while it is further provided with asmall shoulder 38b forming an abutment for the edge ,of one of thehelical grooves of the drill. The location of the latter is thus veryaccurately defined. The shoulder 38b may in fact be formed by an insertfitted in the carrier 38 so as to be vertically adjustable in accordancewith the size of the drill to be ground.

What I claim is:

1. In an apparatus for sharpening drills comprising a frame andagrinding wheel revolubly carried by said frame,ythe"provision of twocarriers for the corresponding ,ends of the drill, the rear drillcarrier including a removable chuck adapted to carry the rear end of thedrill and provided with an axial recess at its rear end, a bracket and astud carried by said bracket and adapted to engage said opening in thechuck and the front carrier being provided with two bearing surfacesperpendicular to each other and adapted to engage the tip of the drill,a sleeve revolubly carried by the frame round an axis parallel with theaxis of the grinding wheel in the'immediate vicinity of the latter andcarrying radially and revolubly the front drill carrier, a rod carriedradially and revolubly by the sleeve in diametrical alignment with thefront drill carrier, a drum adapted to revolve round said rod and theouter surface of which forms a part' cylindrical slideway, the axis ofwhich is directed radially with reference to the rod, aslider to whichthe bracket on the rear drill carrier is secured and having an innercylindrical surface matching the cylindrical slideway of the drum to beshifted angularly thereon in accordance with the cutting angle to beobtained for the drill, said slider being provided with an arcuate slotslidingly fitted over the rod, and a nut screwed over the outer end ofsaid rod and adapted to lock the slider and the drum with reference tothe drum and to the sleeve respectively, said nut forming a handlecontrolling the angular movements of the drum and of the sleeve.

2. In an apparatus for sharpening drills comprising a frame and agrinding wheel revolubly carried by said frame, the provision of twocarriers for the corresponding ends of the drill, the rear drill carrierincluding a removable chuck adapted to carry the rear end of the drilland provided with two diametrically opposed notches and with an axialrecess at its rear end, a bracket and a stud carried by said bracket andadapted to engage said opening in the chuck and the front carrier beingprovided with two bearing surfaces perpendicular to each other andadapted to engage the tip of the drill, a sleeve revolubly carried bythe frame round an axis parallel with the axis of the grinding wheelin-the immediate vicinity of the latter and carrying radially andrevolubly the front drill carrier, a rod carried radially and revolublyby the sleeve in diametrical alignment with the front drill carrier, adrum adapted to revolve around said rod and the outer surface of whichforms a part cylindrical slideway, the axis of which is directedradially with reference to the rod, a slider to which the bracket on therear drill carrier is secured and having an inner cylindrical surfacematching the cylindrical slideway of the drum to be shifted angularlythereon in accordance with the cutting angle to be obtained for thedrill, said slider being'provided with an arcuate slot slidingly fittedover the rod, a catch pivotally secured to the slider and adapted toengage selectively said notches in the chuck to hold the latter incorrespondingly opposed angular positions for the sharpening ofdifierent surfaces of the drill, and a nut screwed over the outer end ofsaid rod and adapted to lock the slider and the drum with reference tothe drum and to the sleeve respectively, said nut forming a handlecontrolling the angular movements of the drum and of the sleeve.

3. In an apparatus for sharpening drills comprising a frame and agrinding wheel revolubly carried by said frame, the provision of twocarriers for the corresponding ends of the drill, the rear drill carrierincluding a removable chuck adapted to carry the rear end of the drilland provided with an axial recess at its rear end, a bracket, a studcarried by said bracket and adapted to engage said opening in the chuckwith a sliding fit and a micrometric screw defining the axial locationof the stud in the chuck and the front carrier being provided with twobearing surfaces perpendicular to each other and adapted to engage thetip of the drill, a sleeve revolubly carried by the frame round an axisparallel with the axis of the grinding wheel in the immediate vicinityof the latter and carrying radially and revolubly the front drillcarrier, a rod carried radially and revolubly by the sleeve indiametrical alignment with the front drill carrier, a

, drum adapted to revolve round said rod and the outer and a nut screwedover the outer end of said rod and adapted to lock the'slider and thedrum with reference to the drum and to the sleeve respectively, said nutforming a handle controlling the angular movements of the drum andof thesleeve.

References Cited in the file of this patent UNITED STATES PATENTS2,344,420 Schwartz Mar. 14, 194.4 2,614,370 Kapnick Oct. 21, 19522,663,126 Amiet Dec. 22, 1953 2,748,543 Pardee June 5, 1956 Nyholm Oct.15, 1957

